Annual mass balances of 'reference' glaciers with more than 30 continued observation years. Mass balance values are given on the left y-axis in the unit meter water equivalent per year (m w.e. a-1). A value of -1.0 m w.e. a-1 corresponds to an annual glacier-wide ice thickness loss of about 1.1 meter. Global values are calculated using only one single value (averaged) for each of 19 mountain regions in order to avoid a bias to well observed regions. The number of 'reference' glaciers with reported data is given on the right y-axis. Note that extreme values before 1960 and in 2015 need to be taken with reservation because of the limited sample size.

Note that extreme values before 1960 and in the latest observation period need to be taken with reservation because of the limited sample size.

Cumulative annual mass balances of 'reference' glaciers with more than 30 continued observation years. Cumulative mass balance values relativ to 1970 are given on the left y-axis in the unit meter water equivalent (m w.e.). A value of -10 m w.e. corresponds to a cumulative glacier-wide ice thickness loss of about 11 meters since 1970. Global values are calculated using only one single value (averaged) for each of 19 mountain regions in order to avoid a bias to well observed regions. Note that extreme values before 1960 and in 2015 need to be taken with reservation because of the limited sample size.